Monday, November 28, 2011

It may just be a “mere” 3-watt IC power amp, but does meticulous circuit layout still matter for the AN214 if you want the ultimate in sound quality?

By: Vanessa Uy

If you have been experienced as I am when it comes to audiophile-grade audio power amplifier design, chances are you may have already encountered power amplifiers whose circuit layouts are definitely not worth the solder that binds them – sound quality wise. But can a reasonably good sounding DIY amplifier still be had without resorting to break-the-bank exotic and esoteric components? Well, the answer is definitely yes, and if you’re interested, read on.

Tweaking does still matter even if you are designing a power amp from a fairly generic circuit. And if possible, you can keep the negative feedback levels of the power amp design to a minimum, provided that the resulting harmonic distortion is reasonably low and of low harmonic order. To my ears, very low measured harmonic distortion never resulted in subjective improvement in sound quality. After all, if mainstream consumer electronic manufacturers like Sony or Pioneer wanted everyone to know how low the harmonic distortion of their power amplifiers are, Sony and Pioneer could have long ago provided as a free add-on 20-thousand US-dollar Hewlett-Packard FFT machines to their power amplifiers.

Even passive parts lay-out is of paramount importance, too. From my experience in designing AN214 power amp modules, I always made sure that the resistors – even if they are not esoteric audiophile-approved types like Vishay – should be oriented in phase on the master board. Proper orientation of resistors on the left and right channel is very important if you want your power amp to have natural-sounding stereo imaging and sound-staging; And orientation of fuses matter too – even changing the power supply fuse from a quick-blow to anti-surge results in a subtle-but-audible change in sound quality.

Lastly, the wiring has to be oriented in the same direction as well. With experience, you could even tweak the sound of your AN214 by strategically using a combination of solid-core and stranded wire where they provide the most benefit in improving subjective sound quality. This is very important when the AN214 you are designing is either used as an audiophile-grade power amplifier or a practice guitar amplifier that you want to sound like an EL84-tube equipped guitar amp.